The skull contains a series of cavities known as paranasal sinuses that are connected by passageways. The paranasal sinuses include frontal sinuses, ethmoid sinuses, sphenoid sinuses and maxillary sinuses. The paranasal sinuses are lined with mucous-producing mucosal tissue and ultimately open into the nasal cavity. Normally, mucous produced by the mucosal tissue slowly drains out of each sinus through an opening known as an ostium. If the mucosal tissue of one of these passageways becomes in flamed for any reason, the cavities which drain through that passageway can become blocked. This blockage can be periodic (resulting in episodes of pain) or chronic. This interference with drainage of mucous (e.g., occlusion of a sinus ostium) can result in mucosal congestion within the paranasal sinuses. Chronic mucosal congestion of the sinuses can cause damage to the epithelium that lines the sinus with subsequent decreased oxygen tension and microbial growth (e.g., a sinus infection).
The term “sinusitis” refers generally to any inflammation or infection of the paranasal sinuses caused by bacteria, viruses, fungi (molds), allergies or combinations thereof. It has been estimated that chronic sinusitis (e.g., lasting more than 3 months or so) results in 18 million to 22 million physician office visits per year in the United States. Patients who suffer from sinusitis typically experience at least some of the following symptoms: headaches or facial pain; nasal congestion or post-nasal drainage; difficulty breathing through one or both nostrils; bad breath; and/or pain in the upper teeth.
One of the ways to treat sinusitis is by restoring the lost mucous flow. The initial therapy is typically drug therapy using anti-inflammatory agents to reduce the inflammation and antibiotics to treat the infection. A large number of patients do not respond to drug therapy. Currently, the gold standard for patients with chronic sinusitis that do not respond to drug therapy is a corrective surgery called Functional Endoscopic Sinus Surgery (FESS).
During FESS, an endoscope is inserted into the nose and, under visualization through the endoscope, the surgeon may remove diseased or hypertrophic tissue or bone and may enlarge the ostia of the sinuses to restore normal drainage of the sinuses. FESS procedures are typically performed with the patient under general anesthesia.
Although FESS continues to be the gold standard therapy for surgical treatment of severe sinus disease, FESS does have several shortcomings. For example, FESS can cause significant post-operative pain. Also, some FESS procedures are associated with significant postoperative bleeding and, as a result, nasal packing is frequently placed in the patient's nose for some period of time following the surgery. Such nasal packing can be uncomfortable and can interfere with normal breathing, eating, drinking etc. Also, some patients remain symptomatic even of ter multiple FESS surgeries. Additionally, some FESS procedures are associated with risks of iatrogenic orbital, intracranial and sinonasal injury. Many otolaryngologists consider FESS an option only for patients who suffer from severe sinus disease (e.g., those showing significant abnormalities under CT scan). Thus, patients with less severe disease may not be considered candidates for FESS. One of the reasons why FESS procedures can be bloody and painful relates to the fact that instruments having straight, rigid shafts are used. In order to target deep areas of the anatomy with such straight rigid instrumentation, the physician needs to resect and remove or otherwise manipulate any anatomical structures that may lie in the direct path of the instruments, regardless of whether those an atomical structures are part of the pathology.
New devices, systems and techniques are being developed for the treatment of sinusitis and other disorders of the ear, nose, throat and paranasal sinuses. For example, various catheters, guidewires and of her devices useable to perform minimally invasive, minimally traumatic ear, nose and throat surgery have been described in U.S. patent application Ser. No. 10/829,917 entitled “Devices, Systems and Methods for Diagnosing and Treating Sinusitis and Other Disorders of the Ears, Nose and/or Throat,” now U.S. Pat. No. 9,654,997, issued Feb. 2, 2010, Ser. No. 10/912,578 entitled “Implantable Device and Methods for Delivering Drugs and Other Substances to Treat Sinusitis and Other Disorders,” now U.S. Pat. No. 7,361,168, issued Apr. 22, 2008, Ser. No. 10/944,270 entitled “Apparatus and Methods for Dilating and Modifying Ostia of Paranasal Sinuses and Other Intranasal or Paranasal Structures” now U.S. Pub. No. 2006/0004323, published on Jan. 5, 2006, Ser. No. 11/037,548 entitled “Devices, Systems and Methods For Treating Disorders of the Ear, Nose and Throat”, now U.S. Pat. No. 7,462,175, issued Dec. 9, 2008, and Ser. No. 11/116,118 entitled “Methods and Devices For Performing Procedures Within the Ear, Nose, Throat and Paranasal Sinuses,” now U.S. Pat. No. 7,720,521, issued May 18, 2010. Each of these applications is hereby incorporated herein, in its entirety, by reference thereto. Many of these new devices, systems and techniques are use able in conjunction with endoscopic, radio graphic and/or electronic assistance to facilitate precise positioning and movement of catheters, guidewires and other devices within the ear, nose, throat and paranasal sinuses and to avoid undesirable trauma or damage to critical anatomical structures such as the eyes, facial nerves and brain.
For example, in one new procedure (referred to in this patent application as a “Flexible Transnasal Sinus Intervention” or FTSI), a dilatation catheter (e.g., a balloon catheter or other type of dilator) is advanced through the nose to a position within the ostium of a paranasal sinus or other location, without requiring removal or surgical alteration of other intranasal anatomical structures. The dilatation catheter is then used to dilate the ostium or other anatomical structures to facilitate natural drainage from the sinus cavity. In some cases, a tubular guide may be initially inserted through the nose and advanced to a position near the sinus ostium and a guidewire may then be advanced through the tubular guide and into the affected paranasal sinus. The dilatation catheter may then be advanced over the guidewire and through the tubular guide to a position where its dilator (e.g., balloon) is positioned within the sinus ostium. The dilator (e.g., balloon) is then expanded causing the ostium to dilate. In some cases, such dilatation of the ostium may fracture, move or remodel bony structures that surround or are adjacent to the ostium. Optionally, in some procedures, irrigation solution and/or therapeutic agents may be infused through a lumen of the dilatation catheter and/or other working devices (e.g., guidewires, catheters, cannula, tubes, dilators, balloons, sub stance injectors, needles, penetrators, cutters, debriders, microdebriders, hemostatic devices, cautery devices, cryosurgical devices, heaters, coolers, scopes, endoscopes, light guides, phototherapy devices, drills, rasps, saws, etc.) may be advanced through the tubular guide and/or over the guidewire to deliver other therapy to the sinus or adjacent tissues during the same procedure in which the FTSI is carried out. It is to be understood that, in FTSI procedures, structures and passageways other than sinus ostia may be dilated using the tools described above, tissue may be resected or ablated, bone may be restructured, drugs or drug delivery systems may be deployed, etc., as described in the documents incorporated herein by reference. Thus, for the purposes of this application the term FTSI will be generally used to refer broadly to all of those procedures, not just dilation of sinus ostia.
In FTSI procedures that include positioning of a guidewire into a paranasal sinus, the placement of the guidewire is typically confirmed by visualizing the procedure under fluoroscopy or other x-ray visualization techniques. Currently, there is no simple and accurate method or apparatus to measure the size of an ostium, and in particular a sinus ostium. Surgeons often approximate the size of an ostium endoscopically by placing a sinus seeker with an atraumatic tip of known diameter near the ostium and estimating the size of the ostium. Unfortunately, this method lacks precision or accuracy in determining the size of an ostium.
Determining the ostium size of a nasal ostium prior to surgery enables the user of a balloon catheter to determine the appropriate amount of inflation needed to open the ostium to a size for sufficient drainage. Being able to accurately measure the ostium size after surgery is also useful in determining if the FTSI procedure was successful or if further treatment is needed. Thus there is a need for methods and devices that can accurately determine the size of the ostium pre-, post-, and during such procedures.